In recent years, small mobile products, such as a mobile phone, equipped with an imaging device (camera module) have become widely popular, and taking pictures instantly with the small mobile products has become a common practice. And as an imaging lens for small imaging devices incorporated in the small mobile products, an imaging lens composed of three lenses has been proposed, because the performance of this imaging lens can be enhanced in comparison with imaging lenses composed of one or two lenses. The imaging lens composed of three lenses includes, in order from the object side to the image surface side, a first lens, a second lens and a third lens (see Patent document 1, for example).
The imaging lens described in Patent document 1 includes, in order from the object side to the image surface side, a first lens having positive refractive power, a second lens composed of a meniscus lens having negative refractive power whose lens surface facing the object side is concave and a third lens having positive refractive power. Here, the reason why a lens having negative refractive power is used for the second lens is to correct favorably the chromatic aberration in particular. Further, in the imaging lens proposed in Patent document 1, a reduction in cost is achieved by using plastic lenses for all of the first to third lenses.